Solve for $t$ : $15 = t + 6$
Answer: Subtract $6$ from both sides: $ \begin{eqnarray} \\ \hphantom{15 {- 6}} &\hphantom{=}& \hphantom{t} \\ 15 &=& t + 6 \\ \\ {-6} && {-6} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ 15 {- 6} &=& t \\ \end{eqnarray} $ Simplify. $ t = 9$